This invention relates to a sound determination method and sound determination apparatus which, based on acoustic signals that are received from a plurality of sound sources by a plurality of sound receivers, determines whether or not there is a specified acoustic signal, and more particularly to a sound determination method and sound determination apparatus for identifying the acoustic signal from the nearest sound source from a sound receiver.
With the current advancement of computer technology, it has become possible to execute processing at practical processing speed even for acoustic signal processing that requires a large quantity of operation processing. Because of this, it is anticipated that multi-channel acoustic signal processing functions using a plurality of microphones become practical. As an example of this, is noise suppression technology. In noise suppression technology, sound from a target sound source, for example the nearest sound source, is identified, and by an operation such as delay-sum beamforming or null beamforming using the incident angle or the arrival time difference of the sound to each microphone that is determined from the incident angle as a variable, the sound from an identified sound source is emphasized, and by suppressing the sound from sound sources other than the identified sound source, the target sound is emphasized and other sounds are suppressed. Also, when the nearby sound source that is the target is moving, the power distribution is typically found using delay-sum beamforming with the incident angle as a variable, and from that power distribution, the sound source is estimated to be located at the angle having the largest power, so the sound coming from that angle is emphasized, and sound coming from angles other than that angle is suppressed.
Also, when a sound is not continuously emitted from the nearby target sound source, the ratio or difference between the power of the estimated ambient noise and the current power is typically used to detect the time interval at which sound is emitted from the nearby target sound source.
Furthermore, in U.S. Pat. No. 6,243,322, a method is disclosed that uses the ratio between the peak value of the power distribution that is found using delay-sum processing (used for delay-sum processing) with the incident angle as a variable and the value at other angles in order to determine whether the incident sound is from the nearby target sound source or from a long distance sound source.